The invention relates to a method for comminuting bituminous coal and transporting comminuted coal having a desired particle size in a slurry form. In particular, the invention provides the use of an aqueous methanol solution for comminuting the coal and as the slurry medium.
As the result of the declining availability of oil, more emphasis has been directed toward the problem of more effective utilization of coal. Two methods are generally used for removing coal from the ground, either strip mining, in which the coal is merely dug out of the ground by mechanical or hydraulic means and transferred to the place of use, or underground mining using methods such as slurry mining, room and pillar, or long wall.
Comminution of coal into pieces of manageable size has been accomplished by mechanical means, explosives or by chemical means.
Processs for chemical comminution of coal, both above ground and below ground have been disclosed in U.S. Pat. Nos. 3,815,826 to Aldrich et al, 3,870,237 to Aldrich and 4,032,193 to Drinkard et al. According to these processes, the interlayer forces at natural interfaces present in the coal is weakened by contact with a number of reagents such as gaseous anhydrous ammonia, liquid anhydrous ammonia, aqueous ammonia, organic solvents, alcohols containing sodium hydroxide, and aqueous solutions of sodium hydroxide.
More recently, it has been proposed to transport coal by pumping it as a slurry through a pipeline using water, methanol, or liquid carbon dioxide as the slurry medium, see U.S. Pat. No. 4,206,610 to Santhanam.
The present invention uses an aqueous methanol solution to comminute run-of-mine crushed bituminous coal and thereafter coal particles having a selected particle size are slurried using an aqueous methanol solution as the slurry medium to provide a stable slurry pumpable through a main slurry pipeline to a coal use point resulting in a coal having improved burning characteristics due to further comminution of the coal during pumping.